Tunable nonlinear absorption properties of TiCT MXene for all-optical bipolar modulation applications.

The demand for ultrafast and multifunctional all-optical modulators based on two-dimensional nonlinear optical materials is continuously growing in the era of big data and artificial intelligence. Herein, we report the experimental realization of the first, to the best of our knowledge, all-optical bipolar modulator that is based on pump intensity-dependent nonlinear absorption of TiCT MXene. This tunable nonlinear absorption with a conversion threshold of approximately 65 GW/cm is characterized and analyzed by the Z-scan technology, and TiCT MXene shows a stronger nonlinear absorption coefficient of 10cm/GW than most of two-dimensional materials.

Triarylmethanol Derivatives with Ultralong Organic Room-Temperature Phosphorescence.

Triphenylmethyl-based compounds such as rhodamines and fluoresceine representing an old and well-known class of triphenylmethane dyes, are widely used in fluorescent labeling of bioimaging. Inspired by ultralong room temperature phosphorescence of triphenylphosphine derivatives, herein we report a methoxy substituted triarylmethanol ((4-methoxyphenyl)diphenylmethanol, LJW-1) exhibits ultralong room temperature phosphorescence (RTP) under ambient condition with afterglows of about 7 seconds. Its multiple C-H ⋅ ⋅ ⋅ π intermolecular interactions, C-H ⋅ ⋅ ⋅ O intermolecular interactions, hydrogen bond and π-π interactions are beneficial for forming rigid environment in the aggregated state which is evidently an important factor in the appearance of excellent RTP.

Ultrafast Charge Transfer-Induced Unusual Nonlinear Optical Response in ReSe/ReS Heterostructure.

Ultrafast charge transfer in van der Waals heterostructures can effectively engineer the optical and electrical properties of two-dimensional semiconductors for designing photonic and optoelectronic devices. However, the nonlinear absorption conversion dynamics with the pump intensity and the underlying physical mechanisms in a type-II heterostructure remain largely unexplored, yet hold considerable potential for all-optical logic gates. Herein, two-dimensional ReSe/ReS heterostructure is designed to realize an unusual transition from reverse saturable absorption to saturable absorption (SA) with a conversion pump intensity threshold of approximately 170 GW/cm.

Incorporating ReS Nanosheet into ZnInS Nanoflower as Synergistic Z-Scheme Photocatalyst for Highly Effective and Stable Visible-Light-Driven Photocatalytic Hydrogen Evolution and Degradation.

Inspired by natural photosynthesis, the visible-light-driven Z-scheme system is very effective and promising for boosting photocatalytic hydrogen production and pollutant degradation. Here, a synergistic Z-scheme photocatalyst is constructed by coupling ReS nanosheet and ZnInS nanoflower and the experimental evidence for this direct Z-scheme heterostructure is provided by X-ray photoelectron spectroscopy, ultraviolet photoelectron spectroscopy, and electron paramagnetic resonance. Consequently, such a unique nanostructure makes this Z-scheme heterostructure exhibit 23.

Facile Synthesis of Quinoline-Substituted 3-Hydroxy-2-oxindoles and 3-Amino-2-oxindoles via a Palladium-Catalyzed Cascade Intramolecular Cyclization/Intermolecular Nucleophilic Addition Reaction.

An efficient cascade intramolecular cyclization/intermolecular nucleophilic addition reaction of allenyl benzoxazinone with isatin or isatin-derived ketimine has been established by using Pd-π-Lewis base catalysis. A series of 3-hydroxy-2-oxindoles and 3-amino-2-oxindoles with quaternary carbon atoms at the C3 position were synthesized in good yields under mild conditions through this protocol.

Aromatic Hydrocarbon Based and Space Interactions Induced Color-tunable Single-component Organic Phosphorescence.

Construction of new system and exploration of new approach are of great importance for the improvement of their photophysical properties to meet the growing various uses of phosphorescent materials. Triphenylmethane (TPM), composed only of carbon and hydrogen, exhibits excellent color tunable phosphorescence in air, with ultralong lifetime (836 ms), and wide color-tunable range (from cyan to green, then to yellow and finally to orange, 525 nm-616 nm). Through careful comparison with the single crystal diffraction structure of tetraphenylmethane (TTPM) and theoretical calculation analysis, we believe that various clusters formed through space interactions are crucial for color-tunable phosphorescence.

Exogenous tannic acid relieves imidacloprid-induced oxidative stress in tea tree by activating antioxidant responses and the flavonoid biosynthetic pathway.

Pesticide stress on plants is receiving increased scrutiny due to its effect on plant secondary metabolism and nutritional quality. Tannic acid (TA) is a natural polyphenolic compound showing excellent antioxidant properties and is involved in alleviating stress. The present study thoroughly investigated the effects and mechanism of exogenous TA on relieving imidacloprid (IMI) stress in tea plants.

Visible-light Excited and Highly Photostable Organic Fluorophore with dual-state Emission.

Organic fluorophores with dual-state emission (DSE) are rare or difficult to observe because most of them display either aggregation-induced emission (AIE) or aggregation-caused quenching (ACQ). Amazing works have been accomplished, yet most of the DSE compounds were excited by UV light which limits their wide application in bioimaging. In this work, we achieved a visible-light excited DSE fluorophore and realized its imaging in SKOV-3 cells and zebrafish.

Color-Tunable Ultralong Organic Phosphorescence: Commercially Available Triphenylmethylamine for UV-Light Response and Anticounterfeiting.

Due to the unclear mechanism and lack of effective design for color-tunable ultralong organic phosphorescence (UOP) in a single-component molecule, the development of new types of single-component UOP materials with color-tunable property remains challenging. Herein, commercially available triphenylmethylamine-based single-component phosphors featuring color-tunablity and ultralong lifetime (0.56 s) are reported.

TiO/BP/g-CN heterojunction photocatalyst for the enhanced photocatalytic degradation of RhB.

The efficiency of graphite carbon nitride (g-CN, CN) as a photocatalyst is limited due to its quick recombination of photogenerated carriers and layer re-stacking. To enhance its photocatalytic activity, a multi-heterojunction photocatalyst was developed using TiO and black phosphorus (BP) coupled with CN through a liquid-phase ultrasonic method. The composite, TiO/BP/CN, demonstrated a wider range of light response and higher photo-induced carrier separation efficiency.

An Imidazo[1,5-a]pyridine Benzopyrylium-Based NIR Fluorescent Probe with Ultra-Large Stokes Shifts for Monitoring SO.

A mitochondria-targeted NIR probe based on the FRET mechanism was developed. It shows ultra-large Stokes shifts (460 nm) and emission shifts (285 nm). Furthermore, we also realized the imaging of SO in living SKOV-3 cells, zebrafish and living mice which may be useful for understanding the biological roles of SO in mitochondria and in vivo.

Direct Z-Scheme SnSe/SnSe Heterostructure Passivated by AlO for Highly Stable and Sensitive Photoelectrochemical Photodetectors.

To mimic the natural photosynthesis system, a Z-scheme heterostructure is proposed as a viable and effective strategy for efficient solar energy utilization such as photocatalysis and photoelectrochemical (PEC) water splitting due to the high carrier separation efficiency, fast charge transport, strong redox, and wide light absorption. However, it remains a huge challenge to form a direct Z-scheme heterostructure due to the internal electric-field restriction and vital band-alignment at the interface. Herein, the van der Waals heterostructure based on the allotrope SnSe and SnSe is designed and synthesized by a two-step vapor phase deposition method to overcome the limitation in the formation of the Z-scheme heterostructure for the first time.

Bi Te /Bi Se /Bi S Cascade Heterostructure for Fast-Response and High-Photoresponsivity Photodetector and High-Efficiency Water Splitting with a Small Bias Voltage.

Large-scale multi-heterostructure and optimal band alignment are significantly challenging but vital for photoelectrochemical (PEC)-type photodetector and water splitting. Herein, the centimeter-scale bismuth chalcogenides-based cascade heterostructure is successfully synthesized by a sequential vapor phase deposition method. The multi-staggered band alignment of Bi Te /Bi Se /Bi S is optimized and verified by X-ray photoelectron spectroscopy.

Palladium-Catalyzed Asymmetric Cascade Intramolecular Cyclization/Intermolecular Michael Addition Reaction of Allenyl Benzoxazinones with 1-Azadienes.

We herein designed and synthesized allenyl benzoxazinones of a novel type, which were then involved in a Pd-catalyzed asymmetric cascade intramolecular cyclization/intermolecular Michael addition reaction with 1-azadienes. A broad range of chiral C2-functionalized quinoline derivatives were afforded in moderate to good yields (up to 93%) with high enantioselectivities (up to 93% ee) in this reaction.

Simple and Commercially Available 6-chloroimidazo[1,2-a]pyridine-2-carboxylic Acid-based Fluorescent Probe for Monitoring pH Changes.

Commercially available compounds that can be directly used as fluorescent probes will greatly promote the development of fluorescent imaging. Based on our previously work related to nitrogen bridgehead heterocycles, herein, a commercially available compound, 6-chloroimidazo[1,2-a]pyridine-2-carboxylic acid, has been detected for monitoring pH value (3.0-7.

SbS/SbSe heterojunction for high-performance photodetection and hydrogen production.

Photoelectrochemical (PEC)-type devices provide promising ways for harvesting solar energy and converting it to electric and chemical energy with a low-cost and simple manufacturing process. However, the high light absorption, fast carrier separation, and low carrier recombination are still great challenges in reaching high performance for PEC devices. As emergent two-dimensional (2D) materials, SbSe and SbS exhibit desirable photoelectric properties due to the narrow bandgap, large optical absorption, and high carrier mobility.

Vertically oriented SnS on MoS nanosheets for high-photoresponsivity and fast-response self-powered photoelectrochemical photodetectors.

Van der Waals heterostructures have great potential for the emerging self-powered photoelectrochemical photodetectors due to their outstanding photoelectric conversion capability and efficient interfacial carrier transportation. By considering the band alignment, structural design, and growth optimization, the heterostructures of vertically oriented SnS with different densities on MoS nanosheets are designed and fabricated using a two-step epitaxial growth method. Compared with SnS, MoS, and low density-vertical SnS/MoS heterostructure, the high density-vertical SnS/MoS heterostructure exhibits largely enhanced self-powered photodetection performances, such as a giant photocurrent density (∼932.

Construction of cyclopentane-fused coumarins DBU-catalyzed [3+2] cycloaddition of 3-homoacyl coumarins with cyclic 1-azadienes.

The metal-free DBU catalyzed [3+2] cycloaddition of 3-homoacyl coumarins with cyclic 1-azadienes proceeded smoothly to furnish the corresponding highly functionalized cyclopentane-fused coumarins with excellent diastereoselectivity and complete chemoselectivity and in good yields under mild conditions.

Access to 6-hydroxy indolizines and related imidazo[1,5-]pyridines through the S2 substitution/condensation/tautomerization cascade process.

A simple and efficient cascade reaction was developed for the construction of hydroxy substituted indolizines from pyrrole-2-carbaldehydes and commercially available 4-halogenated acetoacetic esters. Their optical properties were also evaluated.

Enhanced UV-Vis photodetector performance by optimizing interfacial charge transportation in the heterostructure by SnS and SnSe.

Optimizing interfacial charge transfer in type-II heterostructures, is one promising solution to improve efficiency of the solar energy conversion in photodetectors and solar cells. Herein, the SnS/SnSe/ITO and SnSe/SnS/ITO heterostructures are prepared by two-step physical vapor epitaxial growth. X-ray photoelectron spectroscopy confirms the SnS/SnSe heterostructure belongs to type-II band-alignment.

Improved photocatalytic activity and stability of black phosphorus/multi-walled carbon nanotube hybrid for RhB degradation.

Black phosphorus (BP) is a two-dimensional (2D) semiconductor that has recently attracted much interest due to its unique characteristics. However, BP is susceptible to oxidization under ambient conditions. In this work, a facile one-step route is presented, in which stable P-C bonds were formed by ball milling bulk BP and multi-walled carbon nanotubes (MWCNTs) mixture without any additives.

Layer-Dependent Nonlinear Optical Properties of WS, MoS, and BiS Films Synthesized by Chemical Vapor Deposition.

Two-dimensional (2D) layered materials have shown layer-dependent optical properties in both linear optical and nonlinear optical (NLO) regimes due to prominent interlayer coupling and quantum confinement in an atomic scale. However, the NLO properties become more complicated as both saturable absorption (SA) and reverse saturable absorption (RSA) easily happen in 2D materials, which results in a significant challenge to understand the evolution of nonlinear absorption with layers. Motivated by this, chemical vapor-deposited chalcogenide compounds (WS, MoS, and BiS) are used to investigate the pump intensity and layer number-dependent NLO properties.

Coassembly Behavior and Rheological Properties of a β-Hairpin Peptide with Dicarboxylates.

To understand the molecular interaction mechanism and develop peptide-based hydrogels, a β-hairpin peptide CBHH was used as the model peptide, and its coassembly performance with succinic, malic, and tartaric dicarboxylates has been investigated with circular dichroism spectroscopy (CD) and atomic force microscopy (AFM). The rheological properties and cell culture performance of the coassembled hydrogels have also been assessed. The results showed that the dicarboxylates could induce the folding and self-assembly of the β-hairpin peptide and promote its gelation at low pH.

Preparation of a Novel pH-responsive Fluorescent Probe Based on an Imidazo[1,2-a]indole Fluorophore and its Application in Detecting Extremely Low pH in Saccharomyces cerevisiae.

A novel pH-responsive probe based on an imidazo[1,2-a]indole fluorophore architecture is reported. The probe was highly selective to strongly acidic pH (pK = 3.56) with high sensitivity and a fast response time (within 30 s).